The standard drinking water treatment technologies commonly used today are classified broadly into five categories, 1-filtration: classical filtration (US Patent Application 20060162806, “Drinking Water Pitcher Having a Removable Upper Reservoir”), reverse osmosis (RO) and flocculation chemical treatment/settling); 2-adsoprtion: activated carbon and ion-exchange; 3-chemical oxidation: chlorine, chlorine dioxide (US Patent Application 20160068393, “Process for the Generation of Chlorine Dioxide”), in-situ hypochlorous acid (US Patent Application 2011018035, “Advanced Chlorine Generating System”) sodium hypochlorite, calcium hypochlorite, bromine, ozone and hydrogen peroxide; 4-irradiation: UV, plasma & actinic radiation; and 5-Distillation. Classical filtration, RO, chemical oxidation, adsorption, and radiation are employed commercially for point-of-use water treatment technologies with significant limitations, and where they are discussed in greater details below. A number of technologies are employed for large scale water works where economy of scale can justify the high capital investment, maintenance, infrastructure, and support services (quality assurance/quality control, hazardous material handling, waste disposal, et cetera), the scope and scale of which are not practical for the point of use water treatment process of the ACT water treatment invention.
Micro filtration is effective in removing suspended solids (SS) and microorganisms; however, media blinding from the SS and bio-film formation are problematic. This technology is simple to use, but it is expensive to operate due to the limited life span of the filter media due to blinding. In addition, this technology does not treat naturally dissolved organic carbons, toxic organic by-products, and potentially harmful industrial and pharmaceutical organic compounds. Another limitation of this technology is that it does not treat and remove ionic form of heavy metals. Finally, this technology does not sanitize the water, hence a disinfectant is needed to preserve the filtered water from microbial growth.
RO technology is also commercially available for point-of-use processes as described in US Patent Application 20140183107, “Portable Power Generation and Pressurized Water Filtration Unit,” and US Patent Application 20140110339, “Method for High Efficiency Reverse Osmosis Operation.” However, membrane blinding, large power consumption requirement (high water pressure to overcome the osmonic pressure across a semipermeable membrane), and waste (concentrate water rejection ranges from 20% for new, clean membrane to over 50% for fouled membrane), and hazardous chemicals for clean-in-place process, make it expensive to operate and maintain. RO technology does offer an advantage over micro filtration in that it removes dissolved organic compounds; however, it does not treat and remove ionic heavy metals. Finally, this technology does not sanitize the water, hence a disinfectant is needed to preserve the filtered water from microbial growth.
Adsorption technologies are available commercially, activated carbon media to remove organic compounds, and ion-exchange resin to remove heavy metals. Adsorption is practical for low ppm levels of organic compounds and dissolved ions are described in US Patent Application 20080105620, “Water Purification.” For activated carbon, the efficiency of the media decrease as the active sites are used up or blocked by the SS; consequently, this technology is commonly used in refrigerated water filtration where a high level of water quality is already met. For ion-exchange resin, the efficiency of the media decrease as the active sites are used up by not only by the heavy metals but other naturally present ions (e.g., calcium, manganese, iron, copper, et cetera). Finally, unless the water is sanitized, biofilm formation blocks the active sites, reducing the effectiveness and efficiency of the adsorption bed. The unit cost of treating the water is high due to the operating cost of media replacement. Finally, since the performance of the media is a function of the concentration of the contaminants and flow rate, breakthrough could occur without the end user being aware of it unless the water is analyzed.
UV radiation is effective for disrupting the DNA of microorganisms, inhibiting but not necessarily destroy them. Microorganisms are able to repair and regenerate when the UV radiation source is removed. This technology is employed commercially in drinking water dispensing tanks to limit bacterial growth, US Patent Application 20090242485, “Purified Water Dispensing Machine,” and US Application 20090173616, “Water Ionizing System.” It is also used extensively in the aqua-cultural industry to continuous control and limit microbial growth. US Patent Application 20140356229, UV Devices, System and Methods for UV Sterilization,” and US Patent 20130175460, “Compositions and Methods for UV Sterilization,” US Patent Application 20120235050, “Ultraviolet Irradiation System,” broadly describes the art of using UV for disinfection and sterilization of a container, room, space or defined environment. US Patent Application 20140319374, “Portable Ultraviolet Pulse Oximeter Sanitizer,” and US Patent Application 20110243789, “Flexible Ultraviolet LED Sanitizing Apparatus,” referenced the use of UV radiation in sterilization of drinking water and wastewater. One significant limitation of UV radiation alone is that it is not sufficient to destroy organic compounds, such as, naturally dissolved organic carbons, toxic organic by-products, and potentially harmful industrial and pharmaceutical organic compounds. The emerging field of advanced oxidation using UV-PhotoCatalyst in recent years has been promising in treating organic compounds. UV-Photo Catalyst produces hydroxyl radicals, a strong oxidizer that react with organic compounds, reducing the organic compounds to simpler, less toxic compounds. For large, complex and stable organic compounds, the addition of hydrogen peroxide to a UV-Photo Catalyst system is needed. The photo catalyst process reported in technical literatures were developed as nano size or micron size particles in a fluidized bed reactor, making this technology impractical and expensive to operate since the photo catalyst has to be filtered and recovered, or disposed. Finally, a UV/UV-PhotoCatalyst or UV-PhotoCatalyst/Peroxide system cannot treat and remove heavy metals and SS.
The use of high energy plasma for killing or deactivating bacteria is effective, US Patent Application 20140271354, “Methods and Solutions for Killing or Deactivating Bacteria.” The primary drawback with this technology is the power consumption for generating the high energy plasma. Similar to a UV system, a plasma system cannot treat and remove organic carbon, heavy metals and SS.
Actinic radiation is effective and is used to treat ultrapure water, US Patent Application 20130186835, “Method and System for Providing Ultrapure Water,” US Patent Application 20110210266, “Method of Irradiating a Liquid,” US Patent Application 20110210267, “Actinic Radiation Reactor,” US Patent Application 20110210077, “Method and System for Providing Ultrapure Water.” While this technology is used in the semiconductor industry, it is not safe or practical for drinking water given the secondary treatment step to destroy the free radical.
Chemical oxidation is an effective approach to sanitize the water by killing microorganisms. Innovation in this field continues to be a significant development: US Patent Application 20160068393, “Process for the Generation of Chlorine Dioxide,” US Patent Application 20160024667, “Electrochemical Activation of Water,” US Patent Application 20140360948, “Device and Method for Sanitizing Surfaces and Treating Water Using Ozone,” US Patent Application 20140255565, “Methods of Using Solutions of Hypobromite to Treat Poultry in a Chill Tank During Processing to Increase the Weight of Poultry,” US Patent Application 20140193294, “Ozone Sanitizing System,” US Patent Application 20130284647, “Water Treatment System,” US Patent Application 20060032803, “Method and Apparatus for Purifying Water,” US Patent Application 20050161408, “Method and Apparatus for Purifying Water,” and US Patent Application 2012011803, “Water Filter-Pitcher.”
Distillation is economical and practical for large commercial facility, employing the evaporation of water and consequently condensation the water vapor. Significant energy is needed to evaporate water (heat of vaporization 2257 kJ/kg). This process is economically feasible when there is an abundant of waste heat and/or natural source of cooling. US Patent Application 20140053580, “Systems and Methods for Potable Water Production,” employs the use of a refrigerant to collect and condense moisture in the air. The primary limitation of this approach is the energy requires to operate a refrigerant compressor. However, this technology has the distinct advantage for removing heavy metals and SS, and some organic carbons. A mean of sanitizing the collected water is still required.
The foregoing patent information reflects the state of the art of which the inventor is aware and is tendered with a view toward discharging the inventor's acknowledged duty of candor in disclosing information that may be pertinent to the patentability of the technology described herein. It is respectfully stipulated, however, that the foregoing patent and other information do not teach or render obvious, singly or when considered in combination, the inventor's claimed invention.